“There are no striped passing lines in either direction, but cars continue to pass me,” Koss wrote in a note to me. “I’m a bit confused. Is it legal to pass?”

We’ve all seen solid-line lanes along bad curves, where it would be dangerous to pass another car, or places such as in the Callahan and Sumner tunnels, where extra caution is needed. But the stretch of I-95 Koss refers to is fairly straight and safe, so why need them there?

Even more puzzling, the lines are solid when approaching exits 33 and 34. If you’re in a left-hand lane, you can’t switch lanes to turn off the road!

At least, that’s what I thought. When I see a solid line in the pavement I instinctively think “do not cross.” (As did Koss.) But according to state officials and the Federal Highway Administration, that’s not entirely the case.

“Though discouraged, it is not illegal to cross a single solid white lane line,” Sara Lavoie, spokeswoman for the state Department of Transportation, e-mailed me.

‘Though discour-aged, it is NOT illegal to cross a single solid white lane line.’

The dos and don’ts regarding solid white lane lines come from a federal publication known as the Manual on Uniform Traffic Control Devices, which contains hundreds of rules that states are supposed to follow. Under normal circumstances, solid lines are intended to “discourage” passing, the manual says. Passing is prohibited when lanes are bound by a double set of solid lines, either white or yellow in color.

The rule also holds when you encounter solid white lines separating turning lanes at an intersection. In those cases, the solid lines are for “greater emphasis,” according to the official federal manual.

Still, the topic is a confusing one. The federal manual says that a single solid line could, under “specific” circumstances, prohibit passing. The Massachusetts Driver’s Manual, published by the Registry of Motor Vehicles, says “you should not cross” a solid white line “unless you need to avoid danger.”

State Police officials also advise drivers to follow the stricter guideline.

“While not explicitly illegal, a driver should not cross a solid white line unless he or she needs to take evasive action to avoid danger,” spokesman ­David Procopio e-mailed me. “Generally speaking, a trooper probably will not pull over a motorist who safely crosses a solid white line one time. But someone crossing the line multiple times in view of a trooper will certainly draw attention and further investigation.”

As for why this stretch of I-95 has solid white lines, well, that’s easier to explain. The state has been working on the road since last year to add median barrier walls and shoulders, and during construction the traffic lanes had to be shifted to allow the work to be done.

“To try to reduce the amount of friction created by lane changes through the work zone, solid white lane lines were used rather than broken white lane lines . . . to separate the lanes of traffic,” Lavoie said.

To get rid of the solid white lines, the state has two choices. It can either grind off sections of paint from each line, leaving a dash, or “skip,’’ every 30 feet, or it can wait until the road is resurfaced and paint new dashes from scratch. It’s doing the latter.

“When the last layer of new pavement is installed on the project, the typical permanent lane markings will be installed,” Lavoie said.

Expect the “skips” to return by the end of this year.

Untimely reminders

Andrea Frank of Framingham is one of thousands of Massachusetts drivers who have signed up to receive a free e-mail from the Registry reminding them to renew their license before it expires. Without any warning, however, the state agency discontinued the service this winter.

“The thing that really bothers me is that they didn’t notify those of us who had already signed on to the service that the service had been terminated, so unless we discover this accidentally, as I did, we’re still thinking we’re going to be reminded!” Frank wrote me. “I imagine this was a service that could’ve been completely automated and provided at little or no cost to the state. Why would the RMV discontinue it?”

Lavoie, who is also a Registry
spokeswoman, offered this explanation:

“The company providing the e-mail reminder service free of charge for the RMV was sold. We are in negotiation to determine [whether a] new company will continue the e-mail reminder service,” she wrote me. “At the same time, the RMV is exploring other possible alternatives for offering a reminder service. We’d like to ask drivers to check their license’’ for the expiration date in the meantime. “We know this is an inconvenience but we are working to restore the service.”

During the hiatus, you can sign up for a free reminder from AAA Southern New England. Framingham lawyer Brian Simoneau, an authority I’ve quoted in this column, has also set up a free reminder service through his office; you could ask your insurance company if it offers free reminders as well.

As for the Registry of Motor Vehicles returning to its old system of mailing hard copies of renewal reminders, well, that’s not happening.

As I reported last fall, by switching to e-mail, the state said it saves $600,000 annually on printing and postage.

Permanent record

Your official driving record includes information from the most recent 10 years you’ve been driving, so a speeding violation from 2000, for instance, won’t be mentioned.

But a Waltham reader, who asked that his name not be used, was curious after reading this explanation of driving records in a past column. “Aren’t offenses like OUI and DUI,’’ charges related to drunken driving, “on the RMV record permanently?”

Though I wasn’t originally told so, that is indeed the case, Lavoie said.

“Driving records go back 10 years, but regardless of how old the OUI offense is, it is part of the driving history/record even if it is over 10 years old,” she e-mailed me. “Motor vehicle homicide and out-of-state offenses also remain on the record no matter how many years ago they occurred.”